Phosphor-bronze alloy as raw materials for semi solid metal casting

ABSTRACT

A phosphor-bronze alloy as raw materials for Semi Solid Metal casting has a component composition containing Sn of 4 to 15 mass %, Zr of 0.0005 to 0.04 mass %, P of 0.01 to 0.25 mass %, and a balance of Cu and inevitable impurities, further containing Zn of 0.1 to 7.5 mass % as needed, and further containing one or more kinds of Pb of 0.01 to 4.5 mass %, Bi of 0.01 to 3.0 mass %, Se of 0.03 to 1.0 mass %, and Te of 0.01 to 1.0 mass % as needed.

TECHNICAL FIELD

The present invention relates to a phosphor-bronze alloy as raw materials for Semi Solid Metal casting that can be used to produce a phosphor-bronze alloy cast having fine grains by Semi Solid Metal casting (semi-solid alloy casting) without agitating a molten metal.

Priority is claimed on Japanese Patent Application No. 2006-035003, filed Feb. 13, 2006, the content of which is incorporated herein by reference.

BACKGROUND ART

A Cu—Sn copper alloy containing copper and tin as major components and a minute amount of P is known as a phosphor-bronze alloy. A forging phosphor-bronze alloy having a component composition containing Sn of 3.5 to 9.0 mass %, phosphor of 0.03 to 0.35 mass %, and a balance of Cu and inevitable impurities and a casting phosphor-bronze alloy having a component composition containing Sn of 9.0 to 15.0 mass %, phosphor of 0.05 to 0.5 mass %, and a balance of Cu and inevitable impurities are defined in the JIS standard.

When the phosphor-bronze alloys are melted and cast by the use of known methods, dendritic α primary crystals are crystallized in the molten phosphor-bronze alloys and thus the flowability of the molten alloy is poor, thereby deteriorating the casting property at a low temperature. In order to solve this problem, when a slurry-phase semi-solid phosphor-bronze alloy is produced by strongly agitating the molten phosphor-bronze alloy in a temperature range between the liquidus temperature and the solidus temperature and the semi-solid phosphor-bronze alloy is cast, dendrite generated in the solid-liquid mixture slurry is segmentalized by the agitation and the α primary crystal solid in the solid-liquid mixture slurry is formed in a sphere, thereby maintaining the flowability at a high solid phase ratio. Accordingly, a method of casting a phosphor-bronze alloy cast having a structure including fine grains and granular crystals has been suggested, which is termed a Semi Solid Metal casting method (see Patent Document 1).

[Patent Document 1] Japanese Unexamined Patent Publication No. H6-234049

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

However, in executing the Semi Solid Metal casting method in which the molten metal is agitated, since it is necessary to perform the agitation under the control of a molten metal temperature, an apparatus needs to be increased in size. Accordingly, superfluous gas may be introduced into the molten metal under some conditions. The molten metal temperature needs to be lowered in consideration of wear damage. However, the generation of the dendrite structure cannot be completely suppressed even when the known phosphor-bronze alloy is agitated in a semi-solid state. Accordingly, the flowability of the molten metal is markedly deteriorated, thereby finally causing casting failure.

The invention is contrived in view of the above-mentioned problems. An object of the invention is to provide a phosphor-bronze alloy as raw materials for Semi Solid Metal casting that can produce a phosphor-bronze alloy cast having fine grains by Semi Solid Metal casting without using a member for agitating the molten metal.

Means for Solving the Problems

Therefore, the inventors studied in order to enhance the flowability of the semi-solid phosphor-bronze alloy without using an agitating member for segmentalizing and granulating dendrite in a liquid phase and to produce a phosphor-bronze alloy cast having fine grains without casting failure even when the semi-solid phosphor-bronze alloy is cast at a low temperature. As a result, the following observations (A) to (D) were found,

(A) A semi-solid phosphor-bronze alloy obtained by using a phosphor-bronze alloy, which was obtained by adding Zr of 0.0005 to 0.04 mass % to a phosphor-bronze alloy containing Sn of 4 to 15 mass % and P of 0.01 to 0.25 mass %, as a raw alloy, completely melting the phosphor-bronze alloy into a liquid phase, and cooling the molten phosphor-bronze alloy, and a semi-solid phosphor-bronze alloy obtained by re-melting the ingot are both excellent in flowability. Accordingly, it was found that it is possible to produce a phosphor-bronze alloy cast having fine grains by casting the semi-solid phosphor-bronze alloy and that it is not necessary to perform an agitation process in a semi-solid alloy, unlike in the case of known examples.

(B) A semi-solid phosphor-bronze alloy obtained by using a phosphor-bronze alloy, which was obtained by adding Zn of 0.1 to 7.5 mass % to the phosphor-bronze alloy according to (A) containing Zr of 0.0005 to 0.04 mass % and P of 0.01 to 0.25 mass % as a raw alloy, completely melting the phosphor-bronze alloy into a liquid phase, and cooling the molten phosphor-bronze alloy, and a semi-solid phosphor-bronze alloy obtained by re-melting the ingot are both excellent in flowability. Accordingly, it was found that it is possible to produce a phosphor-bronze alloy cast having fine grains by casting the semi-solid phosphor-bronze alloy and that it is not necessary to perform an agitation process in a semi-solid alloy unlike in the case of known examples.

(C) It was found that a phosphor-bronze alloy having a component composition further containing one or more kinds of Pb of 0.01 to 4.5 mass %, Bi of 0.01 to 3.0 mass %, Se of 0.03 to 1.0 mass %, and Te of 0.01 to 1.0 mass % in addition to the phosphor-bronze alloy according to (A) or (B) exhibits the same advantages.

(D) It was found that the reason for the excellent flowability in the semi-solid alloy state of the phosphor-bronze alloy according to (A), (B), or (C) is that fine and granular α primary crystals are crystallized instead of dendrite in the course of cooling and solidifying the phosphor-bronze alloy according to (A), (B), or (C) after completely melting the phosphor-bronze alloy into a liquid phase and that fine and granular α primary crystals coexist in the liquid phase of the semi-solid phosphor-bronze alloy obtained by re-melting the phosphor-bronze alloy according to (A), (B), or (C).

The invention provides the following based on the above-mentioned study result:

(1) A phosphor-bronze alloy as raw materials for Semi Solid Metal casting, having a component composition containing Sn of 4 to 15 mass %, Zr of 0.0005 to 0.04 mass %, P of 0.01 to 0.25 mass % and a balance of Cu and inevitable impurities.

(2) A phosphor-bronze alloy as raw materials for Semi Solid Metal casting, having a component composition containing Sn of 4 to 15 mass %, Zr of 0.0005 to 0.04 mass %, P of 0.01 to 0.25 mass %, Zn of 0.1 to 7.5 mass %, and a balance of Cu and inevitable impurities.

(3) The component composition of the phosphor-bronze as raw materials for Semi Solid Metal casting according to (1) or (2) may have a component composition further containing one or more kinds of Pb of 0.01 to 4.5 mass %, Bi of 0.01 to 3.0 mass %, Se of 0.03 to 1.0 mass %, and Te of 0.01 to 1.0 mass %.

Advantages of the Invention

When the phosphor-bronze alloy as raw materials for Semi Solid Metal casting according to the invention is melted to produce a semi-solid phosphor-bronze alloy in a solid-liquid mixture slurry and the semi-solid phosphor-bronze alloy is cast using a conventional method, a fine and granular α primary phase is generated or an α solid phase coexists in the liquid phase of the semi-solid phosphor-bronze alloy. Accordingly, even when an agitating apparatus is not used, it is possible to cast the semi-solid phosphor-bronze alloy without damaging the flowability of the semi-solid phosphor-bronze alloy. In addition, it is an advantage that the crystal grains of the phosphor-bronze alloy cast obtained by casting the semi-solid phosphor-bronze alloy are further reduced in size, thereby further enhancing the mechanical strength.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the invention will be described in detail.

A phosphor-bronze alloy as raw materials for Semi Solid Metal casting according to the invention has a component composition containing Sn of 4 to 15 mass %, Zr of 0.0005 to 0.04 mass %, P of 0.01 to 0.25 mass %, and a balance of Cu and inevitable impurities.

The phosphor-bronze alloy as raw materials for Semi Solid Metal casting according to the invention may have a component composition containing Sn of 4 to 15 mass %, Zr of 0.0005 to 0.04 mass %, P of 0.01 to 0.25 mass %, Zn of 0.1 to 7.5 mass % and a balance of Cu and inevitable impurities.

The component composition of the phosphor-bronze alloy as raw materials for Semi Solid Metal casting according to the invention may contain Sn of 4 to 15 mass %, Zr of 0.0005 to 0.04 mass %, P of 0.01 to 0.25 mass %, Zn of 0.1 to 7.5 mass %, and a balance of Cu and inevitable impurities.

An ingot of the phosphor-bronze alloy as raw materials for Semi Solid Metal casting according to the invention, the component composition of which is adjusted, is produced and stored in advance, a semi-solid phosphor-bronze alloy is produced by re-melting a necessary amount of the ingot of the phosphor-bronze alloy as raw materials, and a semi-solid phosphor-bronze alloy cast having fine grains can be manufactured by casting the semi-solid phosphor-bronze alloy.

The reasons for defining the component composition of the raw materials phosphor-bronze alloy for Semi Solid Metal casting according to the invention as described above will be described.

Sn:

Sn has a function of improving the flowability of the molten alloy by means of addition to Cu, improving the corrosion resistance of the cast, and improving the mechanical strength and the wear resistance. When the content is less than 4 mass %, it is not preferable because the mechanical strength is small and the flowability of the molten alloy is reduced. On the other hand, when the content is greater than 15 mass %, it is not preferable because the casting property is deteriorated and the resultant cast is hard and brittle, thus reducing the mechanical strength. Accordingly, the content of Sn contained in the phosphor-bronze alloy for Semi Solid Metal casting according to the invention is defined in the range of 4 mass % to 15 mass %.

Zr:

With its coexistence with P, Zr has a function of promoting the generation of fine and granular α primary crystals in a semi-solid state, improving the flowability of the semi-solid phosphor-bronze alloy, and reducing the size of the crystal grains of the phosphor-bronze alloy cast, When the content thereof is less than 0.0005 mass %, it is not preferable because the reduction in size of the crystal grains is not sufficient. On the other hand, when the content is greater than 0.04 mass %, it is not preferable because the crystal grains of the cast increase in size. Accordingly, the content of Zr contained in the phosphor-bronze alloy as raw materials for Semi Solid Metal casting according to the invention is defined in the range of 0.0005 mass % to 0.04 mass %.

P:

With the coexistence of Zr, P has a function of promoting the generation of fine granular α primary crystals in a semi-solid state, improving the flowability of the semi-solid phosphor-bronze alloy, and reducing the size of the crystal grains of the phosphor-bronze alloy cast. When the content thereof is less than 0.01 mass %, it is not preferable because the reduction in size of the crystal grains is not sufficient. On the other hand, when the content is greater than 0.25 mass %, it is not preferable because intermetallic compounds with a low melting point are generated, making it brittle. Accordingly, the content of P contained in the phosphor-bronze alloy for Semi Solid Metal casting according to the invention is defined in the range of 0.01 mass % to 0.25 mass %. Zn:

Zn has a function of further improving the flowability of the semi-solid phosphor-bronze alloy, lowering the melting point, and enhancing the corrosion resistance and is thus added as needed. When the content thereof is less than 0.1 mass %, it is not preferable because the desired effect is not obtained. On the other hand, when the content thereof is greater than 7.5 mass %, it is not preferable because the flowability of the resultant cast is deteriorated. Accordingly, the content of Zn contained in the phosphor-bronze alloy as raw materials for Semi Solid Metal casting according to the invention is defined in the range of 0.1 mass % to 7.5 mass %.

Other components:

The phosphor-bronze alloy as raw materials for Semi Solid Metal casting according to the invention may further contain one or more kinds of Pb, Bi, Se, and Te and the like as needed. When the components are contained in the phosphor-bronze alloy, it is preferable that the content of Pb be in the range of 0.01 mass % to 4.5 mass %, the content of Bi be in the range of 0.01 mass % to 3.0 mass %, the content of Se be in the range of 0.03 mass % to 1.0 mass %, and the content of Te be in the range of 0.01 mass % to 1.0 mass %.

By making the phosphor-bronze alloy as raw materials for Semi Solid Metal casting according to the invention have the above-mentioned component composition, when the phosphor-bronze alloy as raw materials for Semi Solid Metal casting is melted to produce a semi-solid phosphor-bronze alloy in a solid-liquid mixture slurry and the semi-solid phosphor-bronze alloy is cast using a conventional method, a fine and granular α primary phase is generated or an α solid phase coexists in the liquid phase of the semi-solid phosphor-bronze alloy. Accordingly, even when an agitating apparatus is not used, it is possible to cast the semi-solid phosphor-bronze alloy without damaging the flowability of the semi-solid phosphor-bronze alloy. In addition, it is an advantage that the crystal grains of the phosphor-bronze alloy cast obtained by casting the semi-solid phosphor-bronze alloy are further reduced in size, thereby further enhancing the mechanical strength.

EMBODIMENTS Embodiment 1

By preparing conventional cathode copper as a raw material, feeding the cathode copper into an electrical furnace, melting the cathode copper in an atmosphere of Ar gas, adding Sn and P thereto when the temperature of the molten copper is 1200° C., adding Zn, Pb, Bi, Se, Te, and the like thereto as needed, and finally adding Zr thereto, a molten phosphor-bronze alloy was produced. By casting the molten phosphor-bronze alloy, ingots of phosphor-bronze alloys as raw materials for Semi Solid Metal casting (hereinafter, referred to as phosphor-bronze alloys as raw materials according to examples of the invention) according to Examples 1 to 75 of the invention and phosphor-bronze alloys as raw materials for Semi Solid Metal casting (hereinafter, referred to as phosphor-bronze alloys as raw materials according to comparative examples) according to Comparative Examples 1 to 6, which have the component compositions shown in Tables 1 to 6, were produced.

By melting a phosphor-bronze alloy containing Sn of 9 mass %, P of 0.35 mass % and a balance of Cu and inevitable impurities and being available on the market and a phosphor-bronze alloy containing Sn of 6 mass %, P of 0.1 mass % and a balance of Cu and inevitable impurities and being available on the market in an atmosphere of Ar gas, molten phosphor-bronze alloys of a temperature of 1200° C. were produced. By casting the molten phosphor-bronze alloy, ingots of phosphor-bronze alloys as raw materials for Semi Solid Metal casting (hereinafter, referred to as phosphor-bronze alloys as raw materials according to Conventional Examples) according to Conventional Examples 1 and 2 having the component composition shown in Table 6 were produced.

By cutting out parts of the ingots of the phosphor-bronze alloys as raw materials according to Examples 1 to 75 of the present invention, the phosphor-bronze alloys as raw materials according to Comparative Examples 1 to 6, and the phosphor-bronze alloys as raw materials according to Conventional Examples 1 and 2 and heating the cut-out ingots at a predetermined temperature between the solidus temperature and the liquidus temperature to re-melt the ingots, semi-solid phosphor-bronze alloys were produced. Quenched samples were produced by rapidly quenching the semi-solid phosphor-bronze alloys. By observing the structures of the quenched samples with an optical microscope, the shapes of the α solid phase coexisting with the liquid phase in the semi-solid phosphor-bronze alloys were estimated and the average grain sizes thereof were measured. The results are shown in Tables 1 to 6.

The average grain sizes of the α solid phase were measured by etching the cutting surfaces of the quenched samples with nitric acid and then observing the cutting surfaces with an optical microscope.

TABLE 1 α solid phase in Phosphor- quenched sample bronze as raw Component composition (mass %) Average grain materials Sn Zr P Zn Pb Bi Se Te Cu shape size (μm) The 1 6 0.031 0.08 — — — — — balance granular 100 Present 2 4 0.018 0.01 — — — — — balance granular 200 Invention 3 7 0.015 0.07 — — — — — balance granular 50 4 8 0.0094 0.05 — — — — — balance granular 40 5 9 0.0060 0.09 — — — — — balance granular 30 6 10 0.0015 0.11 — — — — — balance granular 40 7 11 0.0008 0.16 — — — — — balance granular 70 8 12 0.028 0.13 — — — — — balance granular 50 9 13 0.039 0.19 — — — — — balance granular 120 10 14 0.003 0.21 — — — — — balance granular 30 11 15 0.0005 0.25 — — — — — balance granular 120 12 5 0.0008 0.11 7.5 — — — — balance granular 80 13 7 0.0015 0.16 5   — — — — balance granular 50 14 9 0.0060 0.13 2.5 — — — — balance granular 30 15 11 0.0094 0.19 0.3 — — — — balance granular 25

TABLE 2 α solid phase in Phosphor- quenched sample bronze as raw Component composition (mass %) Average grain materials Sn Zr P Zn Pb Bi Se Te Cu shape size (μm) The 16 9 0.0008 0.08 — 4.3 — — — balance granular 80 Present 17 8 0.0015 0.01 — 3.5 — — — balance granular 200 Invention 18 10 0.0060 0.07 — 2.3 — — — balance granular 25 19 11 0.0094 0.05 — 1.1 — — — balance granular 25 20 4 0.015 0.09 — 0.5 — — — balance granular 100 21 7 0.018 0.11 — 0.1 0.72 — — balance granular 45 22 13 0.031 0.16 — 0.02 0.03 0.03 — balance granular 50 23 6 0.028 0.13 — — 2.43 — — balance granular 50 24 7 0.039 0.19 — — 2.35 — — balance granular 100 25 9 0.003 0.21 — — 1.23 — — balance granular 60 26 12 0.0005 0.25 — — 0.66 — — balance granular 150 27 14 0.0003 0.11 — — 0.05 — — balance granular 100 28 8 0.0015 0.16 — — 0.01 0.05 — balance granular 90 29 10 0.0060 0.13 — — 0.02 0.06 0.01 balance granular 25 30 13 0.0094 0.19 — 0.01 — 0.03 0.01 balance granular 50

TABLE 3 α solid phase in Phosphor- quenched sample bronze as raw Component composition (mass %) Average grain materials Sn Zr P Zn Pb Bi Se Te Cu shape size (μm) The 31 5 0.0008 0.08 — — — 0.11 — balance granular 120 Present 32 8 0.0015 0.01 — 0.1  — 0.06 — balance granular 200 Invention 33 10 0.0060 0.07 — — — 0.21 — balance granular 30 34 11 0.0094 0.05 — — 0.3  0.45 — balance granular 25 35 15 0.015 0.09 — — — 0.15 — balance granular 30 36 7 0.018 0.11 — — — 0.7  — balance granular 45 37 4 0.031 0.16 — — — 1.0  — balance granular 120 38 6 0.028 0.13 — 0.01 0.01 0.03 0.01 balance granular 50 39 7 0.039 0.19 — — 0.01 — 0.11 balance granular 100 40 9 0.003 0.21 — 0.01 — — 0.05 balance granular 60 41 12 0.0005 0.25 — — — 0.03 0.08 balance granular 150 42 14 0.0008 0.11 — — — — 0.15 balance granular 100 43 8 0.0015 0.16 — — — — 1.0 balance granular 90 44 10 0.0060 0.13 — — — — 0.7 balance granular 25 45 13 0.0094 0.19 — — — — 0.23 balance granular 50

TABLE 4 α solid phase in Phosphor- quenched sample bronze as raw Component composition (mass %) Average grain materials Sn Zr P Zn Pb Bi Se Te Cu shape size (μm) The 46 5 0.0008 0.08 0.5 4.33 — — — balance granular 100 Present 47 8 0.0015 0.01 2 3.35 — — — balance granular 150 Invention 48 10 0.0060 0.07 4 2.23 — — — balance granular 30 49 11 0.0094 0.05 6 1.11 0.01 — — balance granular 25 50 15 0.015 0.09 0.1 0.5  — 0.03 — balance granular 50 51 7 0.018 0.11 1 0.11 — — 0.01 balance granular 50 52 13 0.031 0.16 4 0.05 — — — balance granular 90 53 6 0.028 0.13 7 — 2.43 — — balance granular 30 54 7 0.039 0.19 2 — 1.85 — — balance granular 120 55 9 0.003 0.21 0.3 — 1.23 — — balance granular 60 56 12 0.0005 0.25 4 — 0.66 0.03 — balance granular 150 57 14 0.0008 0.11 5 — 0.35 — 0.01 balance granular 100 58 8 0.0015 0.16 1 — 0.06 — — balance granular 70 59 10 0.0060 0.13 3 — 0.05 — — balance granular 30 60 13 0.0094 0.19 2 — — 0.03 0.01 balance granular 60

TABLE 5 α solid phase in Phosphor- quenched sample bronze as raw Component composition (mass %) Average grain materials Sn Zr P Zn Pb Bi Se Te Cu shape size (μm) The 61 5 0.0008 0.08 2 — — 0.11 — balance granular 90 Present 62 8 0.0015 0.01 0.3 0.09 0.05 0.06 — balance granular 200 Invention 63 10 0.0060 0.07 4 — — 0.21 — balance granular 30 64 11 0.0094 0.05 7 — — 0.15 — balance granular 60 65 15 0.015 0.09 0.2 — — 0.95 — balance granular 45 66 7 0.018 0.11 3 — — 0.35 — balance granular 50 67 13 0.031 0.16 2 — — 0.35 — balance granular 100 68 6 0.028 0.13 0.5 0.05 0.05 0.03 0.01 balance granular 60 69 7 0.039 0.19 2 — — — 0.11 balance granular 120 70 9 0.003 0.21 3 0.01 — 0.03 0.05 balance granular 60 71 12 0.0005 0.25 4 — 0.01 0.05 0.01 balance granular 150 72 14 0.0008 0.11 0.5 — — — 0.15 balance granular 120 73 8 0.0015 0.16 6 — — — 0.45 balance granular 80 74 10 0.0060 0.13 3 — — — 0.95 balance granular 30 75 13 0.0094 0.19 1 — — — 0.23 balance granular 50

TABLE 6 α solid phase in Phosphor- quenched sample bronze as raw Component composition (mass %) Average grain materials Sn Zr P Zn Pb Bi Se Te Cu shape size (μm) Comparative 1  3* 0.006 0.07 — — — — — balance granular 400 Example 2 16* 0.006 0.07 — — — — — balance dendrite-phase — 3 8 0.0003* 0.07 — — — — — balance dendrite-phase — 4 6 0.042* 0.03 — — — — — balance granular 400 5 10  0.015 0.008* — — — — — balance dendrite-phase — 6 9 0.005 0.26* — — — — — balance dendrite-phase — Conventional 1 9 — 0.35 — — — — — balance dendrite-phase — 2 6 — 0.10 — — — — — balance dendrite-phase — Mark * represents a value departing from the conditions of the present invention.

It is estimated from the results shown in Tables 1 to 6 that the fine and granular α solid phase coexists with the liquid phase in the semi-solid state of the phosphor-bronze alloys as raw materials according to Examples 1 to 75 of the present invention, since the α solid phase of all the quenched samples was finely granular. On the other hand, it is estimated that dendrite was generated in the semi-solid state of the phosphor-bronze alloys as raw materials according to Conventional Examples 1 and 2, since the α solid phase of the quenched samples of the phosphor-bronze alloys as raw materials according to Conventional Examples 1 and 2 was in a dendrite phase.

Accordingly, it can be seen that the semi-solid phosphor-bronze alloys produced from the phosphor-bronze alloys as raw materials according to Examples 1 to 75 of the present invention were better in flowability than the semi-solid phosphor-bronze alloys produced from the phosphor-bronze alloys as raw materials according to Conventional Examples 1 and 2 and that the fine and granular α solid phase was generated in the liquid phase of the semi-solid phosphor-bronze alloys obtained by melting the phosphor-bronze alloys as raw materials according to Examples 1 to 75 of the present invention, thereby obtaining a cast having fine grains even when the semi-solid phosphor-bronze alloy is cast without agitation. It can also be seen that the phosphor-bronze alloys as raw materials according to Comparative Examples 1 to 6 containing Sn, Zr, and P that depart from the conditions of the invention (the range of component composition of the invention) are not preferable since dendrite is generated, the reduction in size of the crystal grains is insufficient in the semi-solid state thereof, or the alloys are brittle.

Embodiment 2

By cutting out parts of the ingots of the phosphor-bronze alloys as raw materials according to Examples 1 to 75 of the present invention, produced in Embodiment 1, the phosphor-bronze alloys as raw materials according to Comparative Examples 1 to 6, and the phosphor-bronze alloys as raw materials according to Conventional Examples 1 and 2 and completely melting the cut-out ingots, molten phosphor-bronze alloys in a liquid phase were produced. Semi-solid phosphor-bronze alloys maintained at a predetermined temperature between the solidus temperature and the liquidus temperature were produced by cooling the molten phosphor-bronze alloy thereafter. Quenched samples were produced by rapidly quenching the semi-solid phosphor-bronze alloys. By observing the structures of the quenched samples with an optical microscope, the shapes of the α solid crystals generated in semi-solid phosphor-bronze alloys were estimated and the average grain sizes thereof were measured. The results were the same as Embodiment 1.

INDUSTRIAL APPLICABILITY

When a phosphor-bronze alloy as raw materials of the present invention for Semi Solid Metal casting is melted to produce a semi-solid phosphor-bronze alloy in a solid-liquid mixture slurry and the semi-solid phosphor-bronze alloy is cast using a conventional method, a fine and granular α primary phase is generated or an α solid phase coexists in the liquid phase of the semi-solid phosphor-bronze alloy. Accordingly, even when an agitating apparatus is not used, it is possible to cast the semi-solid phosphor-bronze alloy without damaging the flowability of the semi-solid phosphor-bronze alloy. In addition, it is an advantage that the crystal grains of the phosphor-bronze alloy cast obtained by Semi Solid Metal casting phosphor-bronze alloy are further reduced in size, thereby further enhancing the mechanical strength. Accordingly, the invention is industrially very useful. 

1. A phosphor-bronze alloy as raw materials for Semi Solid Metal casting having a component composition containing Sn of 4 to 15 mass %, Zr of 0.0005 to 0.04 mass %, P of 0.01 to 0.25 mass %, and a balance of Cu and inevitable impurities.
 2. A phosphor-bronze alloy as raw materials for Semi Solid Metal casting, having a component composition containing Sn of 4 to 15 mass %, Zr of 0.0005 to 0.04 mass %, P of 0.01 to 0.25 mass %, Zn of 0.1 to 7.5 mass %, and a balance of Cu and inevitable impurities.
 3. The phosphor-bronze alloy as raw materials for Semi Solid Metal casting according to claim 1, wherein the component composition further contains one or more kinds of Pb of 0.01 to 4.5 mass %, Bi of 0.01 to 3.0 mass %, Se of 0.03 to 1.0 mass %, and Te of 0.01 to 1.0 mass %.
 4. The phosphor-bronze alloy as raw materials for Semi Solid Metal casting according to claim 2, wherein the component composition further contains one or more kinds of Pb of 0.01 to 4.5 mass %, Bi of 0.01 to 3.0 mass %, Se of 0.03 to 1.0 mass %, and Te of 0.01 to 1.0 mass %. 